{
  "url": "https://openlegislation.uk/eu-directive-2015-996/annex/division-ASSESSMENT/division-2/division-2.5/division-2.5.6/division-9",
  "json_url": "https://openlegislation.uk/eu-directive-2015-996/annex/division-ASSESSMENT/division-2/division-2.5/division-2.5.6/division-9.json",
  "legislation": "eudr/2015/996",
  "legislation_title": "Commission Directive (EU) 2015/996 of 19 May 2015 establishing common noise assessment methods according to Directive 2002/49/EC of the European Parliament and of the Council (Text with EEA relevance)",
  "legislation_url": "https://openlegislation.uk/eu-directive-2015-996",
  "path": "annex/division/ASSESSMENT/division/2/division/2.5/division/2.5.6/division/9",
  "kind": "division",
  "number": null,
  "heading": "Pure diffraction",
  "text": "For pure diffraction, with no ground effects, the attenuation is given by:\nΔdif =\n10 C h × lg 3 + 40 λ C″δ\nif 40 λ C″δ ≥ − 2\n(2.5.21)\n0\notherwise\nwhere\nCh = 1\n(2.5.22)\nλ is the wavelength at the nominal centre frequency of the frequency band considered;\nδ is the path difference between the diffracted path and the direct path (see next subsection on calculation of the path difference);\nC″ is a coefficient used to take into account multiple diffractions:\nC″ = 1 for a single diffraction.\nFor a multiple diffraction, if e is the total distance along the path, O1 to O2 + O2 to O3 + O3 to O4 from the ‘rubber band method’, (see Figures 2.5.d and 2.5.f) and if e exceeds 0,3 m (otherwise C″ = 1), this coefficient is defined by:\n(2.5.23)\nThe values of Δdif shall be bound:\nif Δ dif < 0: Δ dif = 0 dB\nif Δ dif > 25: Δ dif = 25 dB for a diffraction on a horizontal edge and only on the term Δdif which figures in the calculation of Adif . This upper bound shall not be applied in the Δdif terms that intervene in the calculation of Δ ground , or for a diffraction on a vertical edge (lateral diffraction) in the case of industrial noise mapping.",
  "extent": "E+W+S+N.I.",
  "status": null,
  "version": "current",
  "annotations": [],
  "outstanding_effects": [],
  "provenance": {
    "source": "legislation.gov.uk",
    "source_url": "https://www.legislation.gov.uk/eudr/2015/996/annex/division/ASSESSMENT/division/2/division/2.5/division/2.5.6/division/9",
    "retrieved_at": "2026-11-01T15:21:38.862218+00:00"
  },
  "licence": "Open Government Licence v3.0",
  "licence_url": "https://www.nationalarchives.gov.uk/doc/open-government-licence/version/3/",
  "attribution": "Contains public sector information licensed under the Open Government Licence v3.0. Source: legislation.gov.uk, The National Archives."
}